seg

data type for representing line segments or floating-point intervals

seg : data type for representing line segments or floating-point intervals

Overview

ID	Extension	Package	Version	Category	License	Language
3940	seg	seg	`1.4`	TYPE	PostgreSQL	C

Attribute	Has Binary	Has Library	Need Load	Has DDL	Relocatable	Trusted
--s-dt-	No	Yes	No	Yes	no	yes

Relationships
See Also	cube prefix unit ip4r pgmp numeral pg_rational uint uint128 ltree

Packages

PG18	PG17	PG16	PG15	PG14
1.4	1.4	1.4	1.4	1.4

This is a built-in contrib extension ship with the PostgreSQL kernel

Install

Create this extension with:

CREATE EXTENSION seg;

Usage

seg: line segment / floating-point interval data type

The seg extension provides a data type for representing line segments or floating-point intervals, useful for representing measurements with uncertainty.

CREATE EXTENSION seg;

Input Formats

SELECT '5.0'::seg;           -- zero-length interval (point)
SELECT '5.0 .. 7.0'::seg;    -- interval from 5.0 to 7.0
SELECT '5(+-)0.3'::seg;      -- interval 4.7 .. 5.3
SELECT '50 ..'::seg;          -- open interval >= 50
SELECT '.. 0'::seg;           -- open interval <= 0

Certainty indicators (<, >, ~) can be prepended but are treated as comments and ignored by operators.

Operators

Spatial operators (GiST-indexed):

Operator	Description
`<<`	Entirely left of
`>>`	Entirely right of
`&<`	Does not extend right of
`&>`	Does not extend left of
`=`	Equal
`&&`	Overlaps
`@>`	Contains
`<@`	Contained in

Comparison operators (<, <=, >, >=) are available for sorting.

Index Support

CREATE INDEX idx ON measurements USING gist (reading);

Precision

Values are stored as 32-bit floating-point pairs, retaining up to 7 significant digits. Trailing zeroes are preserved.